The Mississippi River, with its sand and silt, has created most of Louisiana, and it could not have done so by remaining in one channel. If it had, southern Louisiana would be a long narrow peninsula reaching into the Gulf of Mexico. Southern Louisiana exists in its present form because the Mississippi River has jumped here and there within an arc about two hundred miles wide, like a pianist playing with one hand—frequently and radically changing course, surging over the left or the right bank to go off in utterly new directions. Always it is the river’s purpose to get to the Gulf by the shortest and steepest gradient. As the mouth advances southward and the river lengthens, the gradient declines, the current slows, and sediment builds up the bed. Eventually, it builds up so much that the river spills to one side. Major shifts of that nature have tended to occur roughly once a millennium. The Mississippi’s main channel of three thousand years ago is now the quiet water of Bayou Teche, which mimics the shape of the Mississippi. Along Bayou Teche, on the high ground of ancient natural levees, are Jeanerette, Breaux Bridge, Broussard, Olivier—arcuate strings of Cajun towns. Eight hundred years before the birth of Christ, the channel was captured from the east. It shifted abruptly and flowed in that direction for about a thousand years. In the second century a.d., it was captured again, and taken south, by the now unprepossessing Bayou Lafourche, which, by the year 1000, was losing its hegemony to the river’s present course, through the region that would be known as Plaquemines. By the nineteen-fifties, the Mississippi River had advanced so far past New Orleans and out into the Gulf that it was about to shift again, and its offspring Atchafalaya was ready to receive it. By the route of the Atchafalaya, the distance across the delta plain was a hundred and forty-five miles—well under half the length of the route of the master stream.That would be fine, except today civilization has built a huge home along the current river and cannot allow the natural course to continue. The phrase, “too big to fail", includes New Orleans remaining a port city, which it would not be if the meandering river were left to nature. As McPhee puts it, “For nature to take its course was simply unthinkable. The Sixth World War would do less damage to southern Louisiana.”
The floods of 1927 brought focus on what could be done – and at what expense. By 1963, the Corps of Engineers had changed the course of the Old River, defining how much water the Atchafalaya would acquire from the Mississippi. A two-fold purpose – be to protect the current infrastructure from being abandoned by the river, and to protect it from destructive flooding.
This year the second protective layer was used, as it was in 1973. Thousands of square miles were flooded by using the planned protection. Thousands of people evacuated. Southern Louisiana was built by silt. No amount of changing nature will change that fact. As the Japanese discovered earlier this year, nature is hard to control.
Think of other cities now considered in harms way -- volcanos, earthquakes, hurricanes, tornados, floods -- can we protect a growing populace against all natural events?
And every one that heareth these sayings of mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it. (Matthew 7:26-27 KJV)